Exosomes are nano-size particles between 40-100 nm in size originally identified as a byproduct of reticulocyte maturation. Exosomes have been described from numerous cell types including tumors, platelets, and immune cells such as dendritic cells. The role of exosomes in immune modulation has been historically restricted to the area of dendritic cell exosomes, which are known to carry MHC molecules, antigens, and both costimulatory and co-inhibitory molecules. The majority of work in the area of exosome immune modulation has focused on stimulation of immunity, particularly in the area of cancer, in which exosome-based vaccines have been developed and entered clinical trials.
Very recently, exosomes have been identified in conditioned media of various stem cell populations including mesenchymal stem cells, and CD34 cells. These exosomes have been studied as “trophic factors” and stimulators of angiogenesis.
However to date, the use of exosomes derived from stem cells for immune modulation has not been performed. Mesenchymal stem cells possess advantages to DC or other immune cells in that they can be generated in large quantities, that their membrane products have an affinity towards the draining lymph node, and that they possess other known regenerative activities.
It is the scope of the current invention to overcome limitations of DC-exosome based immune modulation through the use of MSC.